Supercurrent-carrying density of states in diffusive mesoscopic Josephson weak links

TL;DR

This paper models the supercurrent in diffusive Josephson weak links using quasiclassical Green's functions, achieving quantitative agreement with experiments by considering geometry, energy scales, and interface imperfections.

Contribution

It provides a detailed theoretical framework that accurately describes supercurrent behavior in diffusive Josephson junctions, including effects of nonideal interfaces and additional wires.

Findings

Quantitative agreement with experimental supercurrent data

Impact of interface quality on supercurrent amplitude

Role of geometry and energy scales in supercurrent behavior

Abstract

Recent experiments have demonstrated the nonequilibrium control of the supercurrent through diffusive phase-coherent normal-metal weak links. The experimental results have been accurately described by the quasiclassical Green's function technique in the Keldysh formalism. Taking into account the geometry of the structure, different energy scales and the nonidealities at the interfaces allows us to obtain a quantitative agreement between the theory and the experimental results in both the amplitude and the phase dependence of the supercurrent, with no or very few fitting parameters. Here we discuss the most important factors involved with such comparisons: the ratio between the superconducting order parameter and the Thouless energy of the junction, the effect of additional wires on the weak link, and the effects due to imperfections, most notably due to the nonideal interfaces.